Muslims believe that the Quran was orally revealed by God to the final prophet, Muhammad, through the archangel Gabriel[15][16] incrementally over a period of some 23 years, beginning in the month of Ramadan,[17] when Muhammad was 40; and concluding in 632, the year of his death.[11][18][19] Muslims regard the Quran as Muhammad's most important miracle; a proof of his prophethood;[20] and the culmination of a series of divine messages starting with those revealed to Adam, including the Torah, the Psalms and the Gospel. The word Quran occurs some 70 times in the text itself, and other names and words are also said to refer to the Quran.[21] The Quran is thought by Muslims to be not simply divinely inspired,